1. Field of the Invention
The present invention relates to a seal device. More particularly, this invention relates to a seal device effecting a seal against gaps at the surfaces of assembly components when a distance between the surfaces varies under the influence of external forces, thermal deformation or the like. This invention, for example, relates to a seal device effecting a seal against the surfaces of assembly components subjected to thermal stress in a turbine assembly or the like.
2. Description of the Related Art
Turbine assemblies include turbine sections of steam turbines and assembly unit of compressor and turbine sections of gas turbines or the like. Turbine section 100 of a gas turbine includes moving blade assembly 110 which rotates with a rotor and stationary blade assembly which is fixed in a compartment (not shown). The moving blade assembly 110 consists of a platform 110A which is connected to the rotor and moving blades 110B. The stationary blade assembly, on the other hand, consists of stationary blades, an inner shroud and an outer shroud wherein the inner shroud and the outer shroud are fixed at the both ends of the stationary blades.
A blade surface of the stationary blade and the inner and the outer shrouds form a passage wall for high temperature gas flowing through the turbine part, and also a blade surface of the moving blade 110B and the platform 110A form a passage wall for high temperature gas. Furthermore, in the compartment, a division ring forming a passage wall for high temperature gas together with the blade surface of the certain space between a tip end of the moving blade 110B. The provision ring is formed of a plurality of division ring sections that are connected in the direction of arrangement of moving blade 110B, and forms a wall surface of a circular ring cross section as a whole.
The moving blade assembly 110 as well as the stationary blade assembly have to be arranged to tolerate thermal deformation caused by heat passing through between the blades. Also mounting of a plurality of blades on the shroud section requires the fabrication process to be straightforward. In addition, division of the parts involved is necessary in order to simplify the assembly process and to decrease the associated assembly cost. For these reasons, the moving blade assembly 110 and the stationary blade assembly are divided into a plurality of subassemblies along the circumferential direction of the rotor. That is, the platform sections 110A as well as the shroud sections, like the division ring, are arranged to include a plurality of divided pieces which are adjoined in the direction of arrangement of blade.
When the shroud sections, platform sections 110A and division ring sections are, respectively, connected in the peripheral direction of the rotor, it is necessary to previously keep a gap between the connected shroud sections, between the connected platform sections 110A, between the connected division ring sections. This is because the shroud sections, platform sections and division ring sections will expand by heat in also the peripheral direction due to exposure to high temperature gas, and it is desired to design so that these gaps will completely disappear in the state that these sections expand by heat. In other words, in the condition that high temperature gas flows through the passage formed by the blade surface, shroud, platform or division ring, the high temperature gas will leak outside from the gap formed between the connected platform sections and the like, which may cause decrease in turbine efficiency, or occurrence of unexpected failure at other portions outside the fluid passage by the high temperature gas which is burned gas.
As related art 1 of the present invention, U.S. patent No. 2002/0090296 discloses seal member, spline seal and seal assembly which are used in turbine sections of gas turbines or steam turbines. The seal member, spline seal and seal assembly are mounted at such locations of turbine sections where the assembly gaps of the shrouds or platform are forced to change by hot combustion gases, compression gases or vibratory force.
In U.S. patent No. 2002/0090296, as shown in FIG. 12, a “T”-sectioned seal member 102 is disposed in a gap 112 which is formed between side end surfaces 113, 113 of respective platform sections 110A, 110A. This seal member 102 prevents hot gases V from leaking outside through the gap 112. The seal members 102 are similarly utilized in the gap of segmented rings as well as in the gaps of shrouds. With such a simple “T”-sectioned seal member 102, however, a clearance still remains in the gap unless thermal expansion of the platform sections 110A, 110A causes the respective side end surfaces 113, 113 to be brought into close contact with the seal member 102, and so does leaking outside of the hot gases V. Further, the hot gases V induced into the gasp 112 may damage the side end surfaces 113, 113.
Relative art 2 is disclosed in U.S. Pat. No. 6,162,014 (not shown) in which opposing grooves are defined between the side end surfaces of the platform sections and a spline seal is disposed between the opposing grooves. This spline seal consists of a shim-layer assemblage made of metal surrounded by a cloth-layer assemblage. This spline seal, however, provides a seal against the platform gap in a similar manner to the relative art 1 that the spline seal is laid flat on the bottom surface of the opposing grooves therebetween. That is, the spline seal is configured in such a manner that the opposing groove and the spline seal are arranged in a non-contact state by taking thermal expansion of the platform sections into consideration. For this reason, a fluid-leak problem from the assembled components still arises as it does with U.S. patent No. 2002/0090296 as the relative art 1.
Further according to U.S. Pat. No. 6,193,240, another type of seal assembly is disclosed therein in place of the spline seal of the relative art 2 wherein the seal assembly includes a couple of bight-sectioned large spring leaves and the convex-shaped center sections of the spring leaves abut against each other in a symmetric manner in order to define contact surfaces at both distal sides thereof which come into close contact with the side surfaces of the mounting slot.
This seal assembly, like the relative art 2, is installed in a mounting slot which is defined by two opposing members. For this reason, the contact surfaces of the seal assembly and the abutting surfaces of the mounting slot are arranged to be in resiliently urged, sealing contact wherein the seal assembly includes two adjoined leaves and the respective contact surfaces at longitudinal ends of the leaves are formed by bending toward mutually opposite directions. Longitudinally located both end portions of the leaves in the seal assembly are arranged to stay in a non-contact state against the both bottom surfaces of the opposing slot in consideration of thermal expansion of the platform. For this reason, when a sealed fluid acts on the seal assembly, contact surfaces thereof are forced to lift away from the abutting surfaces to a non-contact state, which leads to a reduced protection against leaking of the sealed fluid and to a reduction of sealing ability. Therefore, even with the above described relative art 3, the seal assembly still is not free from the fluid leakage problem.
The present invention is introduced to resolve the above mentioned problems.
Technical problems which the present invention tries to resolve include improving seal ability of a seal device by maintaining sealing contact of seal surfaces thereof over a wide range of displacement under such circumstances that forces induced by thermal stresses, fluid pressures, vibratory forces or the like cause displacement to a distance between both contact surfaces which mount the seal device therein. Another goal is to assure sealing contact of the seal surfaces after merely mounting the seal device onto between the contact surfaces. Yet another goal is to make an installation of the seal device straightforward and to reduce assembly cost of the components.